Liquid Crystal Display Color Filter Retardation Optimization
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Solution Overview
Problem
Conventional liquid crystal display devices face challenges in maintaining excellent color reproducibility over a wide range of viewing angles and suffer from color shifting issues, particularly when observed from oblique directions in the black state.
Innovation Solution
A liquid crystal display device configuration featuring a pair of polarizing plates with a liquid crystal cell and color filter layers, where the color filter layers have different in-thickness direction retardation values, optimized to minimize color shifting by adjusting the retardation values and layer thicknesses to ensure consistent color representation across various viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional liquid crystal display devices use standard color filter layers with uniform retardation values, then the manufacturing process is simple, but color shifting occurs when viewed from oblique directions
Solution Approach 1:
The patent applies local quality by making each color filter layer (red, green, blue) have different in-thickness direction retardation values tailored to its specific wavelength characteristics. Instead of uniform retardation across all color filters, each layer is optimized with its own retardation value to compensate for viewing angle effects at its specific wavelength, thereby reducing color shifting while maintaining manufacturability through a systematic approach to parameter differentiation.
Solution Approach 2:
The patent implements parameter changes by systematically varying the in-thickness direction retardation values among different color filter layers. Specifically, the red color filter layer has a first retardation value, the green has a second, and the blue has a third, where these values are differently set based on the wavelength characteristics of each color filter. This parameter optimization minimizes color shifting across viewing angles while maintaining manufacturing feasibility.
2Object-affected harmful factors
If optical compensation sheets are added to improve viewing angle characteristics, then color reproduction improves, but device complexity increases
Solution Approach 1:
The patent merges the function of optical compensation with the existing color filter layers by optimizing their retardation values directly. Instead of adding separate optical compensation sheets as a distinct component, the invention integrates the compensation function into the color filter layers themselves through careful selection of their retardation characteristics. This approach improves color reproduction and viewing angle characteristics while avoiding the additional structural complexity that would result from separate compensation sheets.
Solution Approach 2:
The patent applies universality by making the color filter layers serve dual functions: both color filtering and optical compensation. By optimizing the in-thickness direction retardation values of the color filter layers, they simultaneously perform their primary color filtering function and the secondary optical compensation function. This multi-functionality eliminates the need for separate optical compensation components, thereby improving display performance without increasing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces color shifting and maintains excellent color reproducibility even when viewed from oblique directions, enhancing the overall display performance by optimizing the retardation values and layer configurations of the color filters.
Implementation Method 1
The liquid crystal cell takes part in ON-OFF display based on difference in the state of alignment of the liquid crystal molecules
Implementation Method 2
A liquid crystal cell generally comprises liquid crystal molecules, two substrates encapsulating and holding them in between, and an electrode layer applying voltage to the liquid crystal molecules, and polarizing plate(s) disposed on the outer side thereof
Implementation Method 3
Use of the optical compensation sheet, designed to have optical characteristics optimized at each wavelength of light, can provide a liquid crystal display device less causative of color changes depending on the viewing angle
Data Source
AI summary
A novel liquid crystal display device is disclosed. It comprises, at least, a pair of polarizing plates, and a liquid crystal cell, disposed between the pair of polarizing plates, comprising a pair of substrates opposed to each other, electrodes disposed on at least one of the pair of substrates, capable of forming an electric field including a component parallel to the pair of substrates, liquid crystal layer, of which alignment is controlled, disposed between the pair of substrates, a plurality of pixel regions respectively having first, second and third pixels, and a plurality of color filter layers, respectively having first, second and third color filter layers, each corresponding to the first, second and third pixel regions, wherein Rth is different between at least two of the first, second and third color filter layers.